Dear BEE-L readers,

I’ve been following the discussion about neonics and CCD for some time and 
really appreciate the open exchange of opinions.  In that spirit, I’d like 
to respond to some of the recent comments Bob Harrison has posted about 
neonics and Bayer CropScience.  For those who do not know me, I’m the head 
of the Ecotoxicology unit in North America of Bayer CropScience.    

Bob wrote: “We are talking sub lethal effects. NOT LD50.  ALL Bayer 
research is based on LD50.”

Actually, Bayer’s research does address sub-lethal effects. Same is true of 
much non-Bayer sponsored research.  Several summary papers by Bayer 
scientists have appeared over the years that discussed no observed adverse 
effect levels.  These NOAELs are all based on sub-lethal effects.  See 
Schmuck et al. (2001. Pest Manag Sci 57:225-238) and Maus et al. (2003, 
Bulletin of Insectology 56 (1): 51-58).  

Bob wrote:  “They did no sub lethal research nor does Bayer labs own a 
single bee hive!”

Bayer has a full time beekeeper on staff and owns many hives.  We’ve had 
this in-house bee research capacity since before I joined the company 21 
years ago. We thoroughly research the bee safety of every product we 
develop.  

Bob wrote: “Until you post research saying the sub lethal effects of the 
neonicotinoids are not causing problems then expect a response from me.” 
and “Show me some sub lethal research?”

There are scores of relevant studies.  Sub-lethal endpoints that have been 
evaluated include foraging behavior, fecundity, brood development, honey 
production, hive performance and yes, the ability of foraging bees to 
return to the hive (more on this one later).  Sub-lethal endpoints have 
been evaluated in special experiments as well as in semi-field (i.e., 
tunnel or tent studies) and field studies.  The review paper by Maus et al 
(2003) discussed results of 18 semi-field and 14 field studies with 
imidacloprid that were conducted between 1995 and 2001.  The goal of these 
studies was to evaluate what happens when bees encounter crops treated with 
imidacloprid under conditions of practical use.  In every case, no adverse 
effects were observed.  Not even once.  There have been many more such 
studies on imidacloprid and other neonics in subsequent years.  For 
example, Elzen et al. (2004, J. Econ Entomol 97(5) 1513-1516) studied the 
response of bee colonies to imidacloprid treatment of melon fields and 
Cutler et al. (2007, J. Econ. Entomol. 100(3):765-772) studied the response 
of bee colonies to clothianidin seed-treated canola fields.  

Another bit of relevant research on “sub-lethal effects” was presented at 
the 2006 EurBee meeting and the abstract was posted to this list by Randy 
Oliver on 30 September 2007.  This study tested whether exposure to 
imidacloprid in combination with other stressors including Varroa and 
Nosema ceranae, caused effects greater than those of the individuals 
stressors alone.  Here again is the title, author list and conclusion.  The 
full abstract is in the BEE-L archives (and also obtainable from 
EurBee.org).

INTOXICATION OF HONEYBEES – INTERACTIONS OF PLANT PROTECTION PRODUCTS AND 
OTHER FACTORS.  Martina Wehling, Werner von der Ohe, Dietrich Brasse, Rolf 
Forster

“From the findings of chronic feeding tests and semi-field test it can be 
concluded that imidacloprid used as standard seed dressing formulation will 
pose no risks to honeybees.”

Bob wrote:  “Proving a negative?  In Italy the research testing sub lethal 
effects was straight forward.  Each level of expose caused certain problems 
in the bees. Sub lethal testing is not rocket science.”

While Lloyd’s original point that you can never prove a negative is 
correct, you can test whether predictions of an underlying hypothesis are 
consistent with observations either generally available or generated via 
experimentation.  The “sub-lethal” adverse effects that are commonly 
mentioned as being of concern are (1) disorientation (foragers not 
returning to the hive) and (2) suppression of the immune system with the 
result that the hive succumbs to common pathogens.  If either of these 
effects occurred, one should see a dwindling of the population of 
imidacloprid-exposed hives.  This has been looked for in >30 experiments 
and field studies and it has NEVER happened.  That’s pretty compelling 
evidence this hypothesis is not correct.    

But what about the “Italian study” which showed bees didn’t return to the 
hive when feeding on syrup containing imidacloprid?  I assume Bob means the 
study of Bortolotti et al. (Bull. of Insectology 56(1):63-67, 2003).  They 
tested three exposure concentrations, 100, 500 and 1000 ppb and the number 
of bees returning was greatly reduced at the two higher test levels (500 
and 1000 ppb).  But these are concentrations far greater than anything bees 
are likely to be exposed to, and in fact it could be argued they aren’t 
even sub-lethal.  Take the lowest published oral LD50 value for 
imidacloprid (3.7 ng/bee) and convert it to an equivalent food 
concentration (you do this by dividing by the amount of food (26 mg) bees 
ingest on average during acute oral tests).  3.7 ng / 26 mg = a 
concentration of 142 ppb.  Looking at all available data, the threshold for 
knock-down and lethal effects in Bayer studies is about 100 ppb.  With this 
perspective, the finding by Bortolotti et al. that bees don’t return to the 
hive when exposed to 500 and 1000 ppb is hardly a surprise.  Nor does it 
support a conclusion that use of neonics will cause a problem.   

Bob said:  “Bayer first fought French beeks by blaming varroa! At the time 
the French beeks had a excellent varroa control to use. Sorry Bayer.”

A comprehensive multiyear study of the factors that caused the famous bee 
losses in France was made by the AFFSA (French Food Safety Agency) bee 
research unit.  It concluded varroa was indeed a major factor.  Their 
report was released in April and is accessible at 

http://www.afssa.fr/index.htm   

Search the news archives for the press release from April 2, 2008.  There 
is a link to the full report (in French) in the press release.    

The AFFSA bee research team has also weighed in on the hypothesis that 
imidacloprid was responsible for the massive bee losses experienced by 
French beekeepers.  Again, Randy Oliver posted an abstract on 30 Sept 2007 
of this group’s presentation to the EurBee 96 meeting.  You can check the 
BEE-L archives to get the whole thing.  I’ve repeated the title, author 
list and main conclusion here.  

IMIDACLOPRID AND BEE MORTALITY IN FRANCE
M. Aubert, J.-P.Faucon, A.-C.  Martel and  M.-P.Chauzat 
	“We conclude that, if contamination by imidacloprid from sunflower 
cultures issued from treated seeds may have occurred simultaneously with a 
period of colony losses as described by several	French bee-keepers, such 
occurrence has not been observed systematically, and no negative impact on 
bee colonies of the use of Gaucho® has been experimentally demonstrated in 
the field.”

You may also want to read the following publication.  
	Faucon, J.-P.; Clément, A.; Drajnudel, P.; Mathieu, L.; Ribière, 
M.; Martel, A.-C.; Zeggane, S.; Chauzat, M.-P.; Aubert, M. F. (2005): 
Experimental study on the toxicity of imidacloprid given in syrup to honey 
bee (Apis mellifera) colonies. Pest Management 	Science; 61 (2), 111-125

Bob said:  “I approached Bayer about funding sub lethal testing of 
imidacloprid on bees but the company declined.  The national organizations 
tried! forty grand to Penn State to settle the issue seemed like chump 
change but the company declined.”  

I find this a very hard to believe.  Who did you approach at Bayer?  I’ve 
asked around the company and nobody has any recollection of such a 
request.  Such requests should get forwarded to me.  Yours did not.  I’m 
not impossible to reach.  David Mendes has gotten through and I sent him a 
bunch of information.  Others who post regularly to this list have talked 
to me on the phone as well.  Also, nobody from the national organizations 
approach Bayer with any proposal.  

Bayer has never been asked to contribute funds to any of the Penn State 
work.  When they were first getting started, they asked for analytical 
standards and advice on analytical methodology which we provided.   

Bob wrote: “So now the study is coming. A company rep said off the record 
that they would denounce findings that sub lethal effects hurt bees on the 
grounds the study was funded by beekeepers and the researchers were 
biased.”  

Any technical opinion from Bayer would come from my team.  Our comments 
would be based on the scientific merits of the work.  I find it very hard 
to believe a Bayer rep said what you claim.  

Bob wrote: “All the beekeepers in the U.S. are asking for is some label 
changes. Bayer will not even sit down with us and talk. Printed company 
positions have been sent to both groups.”  

Again, I checked around the company and no such meeting has been proposed 
to Bayer CropScience.  If asked, and assuming the request came from the 
leadership of one of the beekeeping organizations, I’d be very surprised if 
Bayer wouldn’t agree to meet.  We do however stand behind our labels as we 
have extensive research that shows our products are safe when used as 
directed.  

Maybe the label changes Bob seeks are for the product ASSAIL (acetamiprid) 
since the following is mentioned in a string of posts on July 9 about this 
product. 

“All beeks are asking for is a few label changes. If Bayer would meet and 
discuss then the tension would ease in my opinion.”  

Bayer does not sell ASSAIL or any other products containing acetamiprid.  I 
do know quite a bit about this chemical however.  It (along with 
thiacloprid) are the two neonics that are not very toxic to bees.  They are 
1000 times less toxic than the nitroguanidines (imidacloprid, thiamethoxam, 
etc.).  If I was a beekeeper, rather than pressuring growers to use 
something else, this is a product I would be encouraging them to use.  You 
aren’t going to find many alternative insecticide treatments safer to honey 
bees than ASSAIL.  To comply with the label restriction, the application 
can be made late in the day or at night.       

Want more information on Neonics and honey bees?  Bayer has a technical FAQ 
document on neonics and bees.  It has much more info and citations than I 
have space for here.  We sent it around to the CCD research community last 
year but I'm not sure if it was passed on.  If anyone on the list wants a 
copy, drop me an e-mail and I’ll send it to you.  

Best regards to all,

Dave Fischer
Director, Ecotoxicology 
Research and Development Department
Bayer CropScience LP
2 T.W. Alexander Drive
PO Box 12014
Research Triangle Park, NC 27709
[log in to unmask]

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